HomePNA or HPNA is a de facto home networking standard developed by the Home Phoneline Networking Alliance. HPNA allows all the components of a home network to interact over the home's existing telephone wiring without disrupting voice capability. In the same way a LAN operates, home networking processes, manages, transports and stores information, which enables disparate devices in a home network such as telephones, fax machines, desktops, laptops, printers, scanners and Web cameras to connect and integrate over an existing wiring topology.
To create the home network, personal computers may be equipped with an HPNA network and HPNA software. An HPNA network may be implemented as an internal PC network interface card (NICs) that includes telephone jacks on the back for connection to the network. An HPNA network may also be implemented in an external USB adapter that plugs into the USB port on the PC on one end, while the other end connects to the phone line at the wall jack. Additionally, an HPNA network may be implemented as part of the chipset or ACR (Advanced Communications Riser).
FIG. 1 illustrates an embodiment of a home phone line network that complies with the Home Phoneline Networking Alliance (HPNA) specification version 2.0. The network allows multiple computers to communicate through telephone wires of residential homes. The network includes an application program running on the PC called a host ethernet media access controller (MAC) 112, and an HPNA chip 100 for implementing the HPNA 2.0 specification, which is included on a network interface card. The HPNA chip 100 includes a Media Independent Interface (MII) 106, a Media access controller (MAC) 108, and a Physical Layer (PHY) 110.
The host ethernet MAC 112 sends frames of data packets out over the home network, and receives frames of data packets from the network, through the HPNA chip 100. The HPNA chip 100 communicates with an analog front end (AFE) 104 that processes signals between the chip 100 and the transmission channel, which in this case are the telephone wires of the house that are accessed via a phone jack 102. The AFE 104 converts outgoing digital signals into analog signals, and converts incoming analog signals into digital signals.
HomePNA 10M8 provides for a wide range of bit rates ranging from 4 Mb/s to 32 Mb/s. When receiving data off the wire, the HPNA chip 100 can never fall behind the maximum arrival rate of new packet data. When transmitting data from the host ethernet MAC 112 to the HPNA chip 100, however, it is possible for the host ethernet MAC 112 to fall into an underflow condition, which causes the host ethernet MAC 112 and the HPNA chip 100 to become unsynchronized when transferring frames of packets. More specifically, when transmitting data to the HPNA chip 100, the host ethernet MAC 112 transmits a control frame followed by an Ethernet data frame. During an underflow condition, the HPNA chip 100 may encounter situations where the control frames become unsynchronized with the data frames, hampering network reliability and performance.
Accordingly, what is needed is a method and system for maintaining synchronization between the control frame and data frame pairs between the host ethernet MAC and HPNA chip. The present invention addresses such a need.